Project description:A quantitative proteomic data was performed to identify the phosphorylated proteins and dynamic abundance during maize endosperm filling.
Project description:The grain filling rate is closely associated with final grain yield of maize during the period of maize grain filling. To identify the key microRNAs (miRNAs) and miRNA-dependent gene regulation networks of grain filling in maize, a deep-sequencing technique was used to research the dynamic expression patterns of miRNAs at four distinct developmental grain filling stages in Zhengdan 958, which is an elite hybrid and cultivated widely in China. The sequencing result showed that the expression amount of almost all miRNAs was changing with the development of the grain filling and formed in seven groups. After normalization, 77 conserved miRNAs and 74 novel miRNAs were co-detected in these four samples. Eighty-one out of 162 targets of the conserved miRNAs belonged to transcriptional regulation (81, 50%), followed by oxidoreductase activity (18, 11%), signal transduction (16, 10%) and development (15, 9%). The result showed that miRNA 156, 393, 396 and 397, with their respective targets, might play key roles in the grain filling rate by regulating maize growth, development and environment stress response. The result also offered novel insights into the dynamic change of miRNAs during the developing process of maize kernels and assisted in the understanding of how miRNAs are functioning about the grain filling rate.
Project description:BackgroundConcentrations of cadmium (Cd) in the grain of many durum wheats (Triticum turgidum subsp. durum) grown in North American prairie soils often exceed international trade standards. Genotypic differences in root-to-shoot translocation of Cd are a major determinant of intraspecific variation in the accumulation of Cd in grain. We tested the extent to which changes in whole-plant Cd accumulation and the distribution of Cd between tissues influences Cd accumulation in grain by measuring Cd accumulation throughout the grain filling period in two near-isogenic lines (NILs) of durum wheat that differ in grain Cd accumulation.ResultsRoots absorbed Cd and transported it to the shoots throughout the grain filling period, but the low- and high-Cd NILs did not differ in whole-plant Cd uptake. Although the majority of Cd accumulation was retained in the roots, the low- and high-Cd NILs differed substantively in root-to-shoot translocation of Cd. At grain maturity, accumulation of Cd in the shoots was 13% (low-Cd NIL) or 37% (high-Cd NIL) of whole-plant Cd accumulation. Accumulation of Cd in all shoot tissue, including grain, was at least 2-fold greater in the high-Cd NIL at all harvests. There was no net remobilization of shoot Cd pools during grain filling. The timing of Cd accumulation in grain was positively correlated with grain biomass accumulation, and the rate of grain filling peaked between 14 and 28 days post-anthesis, when both NILs accumulated 60% of total grain biomass and 61-66% of total grain Cd content.ConclusionsThese results show that genotypic variation in root-to-shoot translocation of Cd controls accumulation of Cd in durum wheat grain. Continued uptake of Cd by roots and the absence of net remobilization of Cd from leaves during grain filling support a direct pathway of Cd transport from roots to grain via xylem-to-phloem transfer in the stem.
Project description:High temperatures significantly impair plant growth and development by restricting maize grain filling; however, the molecular mechanisms underlying heat stress remain poorly understood. In this study, 350 maize inbred lines were evaluated under field conditions, leading to the identification of heat-tolerant Zheng58 and heat-sensitive Qi319. The two inbred lines were exposed to controlled conditions of 30°C/20°C (optimal) and 42°C/30°C (heat stress) during the grain filling period. Heat stress significantly reduced thousand-kernel weight and seed setting rates, with Qi319 experiencing more pronounced declines. In contrast, Zheng58 showed superior performance, with a grain filling rate 48% higher and seed setting rate 57% greater than Qi319. Transcriptome analysis showed that heat stress disrupted starch biosynthesis and hormonal homeostasis, notably affecting abscisic acid and auxin pathways. Additionally, photosynthetic and transpiration rates in panicle leaves were reduced due to the downregulation of genes related to light-harvesting complexes, photosystem I subunits, and water transport. These findings highlight the critical roles of starch metabolism, hormonal regulation, and photosynthetic efficiency in heat tolerance, offering valuable insights for developing heat-resilient maize varieties to mitigate yield losses under high-temperature conditions.
Project description:ObjectivesRemotely sensed hyperspectral data are increasingly being used to assess crop development and growth throughout the growing season. Large datasets capturing key growth stages can be useful to researchers studying many physiological plant responses. A time series analysis of hyperspectral reflectance measurements taken during the grain filling period and published within a publicly accessible database are described herein. These datasets document the spectral reflectance pattern of the canopy within the visible and near-infrared portion of the electromagnetic spectrum during the late stages of the grain filling period as plants approach and reach physiological maturity.Data descriptionIncluded within the data repository are canopy-level hyperspectral datasets collected in 2017 and 2018. Data is included in its raw form, as well as with several manipulations to smooth and standardize the raw data. Data are released as comma separated value spreadsheets as well as Microsoft Excel open XLSX spreadsheets. These are accompanied by README text files which further describe the data and supplemental files that record hybrids used and plant phenology for each year of data collection.
Project description:Rice poses a major source of the toxic contaminant cadmium (Cd) for humans. Here, we elucidated the role of Cd storage forms (i.e., the chemical Cd speciation) on the dynamics of Cd within rice. In a pot trial, we grew rice on a Cd-contaminated soil in upland conditions and sampled roots and shoots parts at flowering and maturity. Cd concentrations, isotope ratios, Cd speciation (X-ray absorption spectroscopy), and micronutrient concentrations were analyzed. During grain filling, Cd and preferentially light Cd isotopes were strongly retained in roots where the Cd storage form did not change (Cd bound to thiols, Cd-S = 100%). In the same period, no net change of Cd mass occurred in roots and shoots, and the shoots became enriched in heavy isotopes (Δ114/110Cd maturity-flowering = 0.14 ± 0.04‰). These results are consistent with a sequestration of Cd in root vacuoles that includes strong binding of Cd to thiol containing ligands that favor light isotopes, with a small fraction of Cd strongly enriched in heavy isotopes being transferred to shoots during grain filling. The Cd speciation in the shoots changed from predominantly Cd-S (72%) to Cd bound to O ligands (Cd-O, 80%) during grain filling. Cd-O may represent Cd binding to organic acids in vacuoles and/or binding to cell walls in the apoplast. Despite this change of ligands, which was attributed to plant senescence, Cd was largely immobile in the shoots since only 0.77% of Cd in the shoots were transferred into the grains. Thus, both storage forms (Cd-S and Cd-O) contributed to the retention of Cd in the straw. Cd was mainly bound to S in nodes I and grains (Cd-S > 84%), and these organs were strongly enriched in heavy isotopes compared to straw (Δ114/110Cd grains/nodes- straw = 0.66-0.72‰) and flag leaves (Δ114/110Cd grains/nodes-flag leaves = 0.49-0.52‰). Hence, xylem to phloem transfer in the node favors heavy isotopes, and the Cd-S form may persist during the transfer of Cd from node to grain. This study highlights the importance of Cd storage forms during its journey to grain and potentially into the food chain.
Project description:Although the remobilization of vegetative nitrogen (N) and post-silking N both contribute to grain N in maize (Zea mays L.), their regulation by grain sink strength is poorly understood. Here we use 15N labeling to analyze the dynamic behaviors of both pre- and post-silking N in relation to source and sink manipulation in maize plants. The results showed that the remobilization of pre-silking N started immediately after silking and the remobilized pre-silking N had a greater contribution to grain N during early grain filling, with post-silking N importance increasing during the later filling stage. The amount of post-silking N uptake was largely driven by post-silking dry matter accumulation in both grain as well as vegetative organs. Prevention of pollination during silking had less effect on post-silking N uptake, as a consequence of compensatory growth of stems, husk + cob and roots. Also, leaves continuously export N even though grain sink was removed. The remobilization efficiency of N in the leaf and stem increased with increasing grain yield (hence N requirement). It is suggested that the remobilization of N in the leaf is controlled by sink strength but not the leaf per se. Enhancing post-silking N uptake rather than N remobilization is more likely to increase grain N accumulation.
Project description:Grain filling during the linear phase contributes most of the dry matter accumulated in the maize kernel, which in turn determines the final grain yield. Endosperms and embryos of three elite maize hybrids (Zhengdan 958, Nongda 108, and Pioneer 335) were sampled 17, 22, 25, and 28 days after pollination, during the linear phase of grain filling, for proteomic analysis to explore the regulatory factors critical for grain filling rate. In total, 39 and 43 protein spots that showed more than 2-fold changes in abundance at P<0.01 between any two sampling stages in the endosperm and embryo were analyzed by protein mass spectrometry. The changing patterns in expression index of these proteins in the endosperm were evenly distributed, whereas up-regulation patterns predominated (74%) in the embryo. Functional analysis revealed that metabolism was the largest category, represented by nine proteins in the endosperm and 12 proteins in the embryo, of the proteins that significantly changed in abundance. Glycolysis, a critical process both for glucose conversion into pyruvate and for release of free energy and reducing power, and proteins related to redox homeostasis were emphasized in the endosperm. Additionally, lipid, nitrogen, and inositol metabolism related to fatty acid biosynthesis and late embryogenesis abundant proteins were emphasized in the embryo. One protein related to cellular redox equilibrium, which showed a more than 50-fold change in abundance and was co-localized with a quantitative trait locus for grain yield on chromosome 1, was further investigated by transcriptional profile implying consistent expression pattern with protein accumulation. The present results provide a first step towards elucidation of the gene network responsible for regulation of grain filling in maize.
Project description:Nitrogen (N) plays a vital role in photosynthesis and crop productivity. Maize plants may be able to increase physiological N utilization efficiency (NUtE) under low-N stress by increasing photosynthetic rate (P n) per unit leaf N, that is, photosynthetic N-use efficiency (PNUE). In this study, we analyzed the relationship between PNUE and N allocation in maize ear-leaves during the grain-filling stage under low N (no N application) and high N (180 kg N ha(-1)) in a 2-year field experiment. Under low N, grain yield decreased while NUtE increased. Low-N treatment reduced the specific N content of ear leaves by 38% without significant influencing P n, thereby increasing PNUE by 54%. Under low-N stress, maize plants tended to invest relatively more N into bioenergetics to sustain electron transport. In contrast, N allocated to chlorophyll and light-harvesting proteins was reduced to control excess electron production. Soluble proteins were reduced to shrink the N storage reservoir. We conclude that optimization of N allocation within leaves is a key adaptive mechanism to maximize P n and crop productivity when N is limited during the grain-filling stage in maize under low-N conditions.
Project description:Heat stress is a primary constraint to Australia's barley production. In addition to impacting grain yield, it adversely affects physical grain quality (weight and plumpness) and market value. The incidence of heat stress during grain filling is rising with global warming. However, breeding for new superior heat-tolerant genotypes has been challenging due to the narrow window of sensitivity, the unpredictable nature of heat stress, and its frequent co-occurrence with drought stress. Greater scientific knowledge regarding traits and mechanisms associated with heat tolerance would help develop more efficient selection methods. Our objective was to assess 157 barley varieties of contrasting genetic backgrounds for various developmental, agro-morphological, and physiological traits to examine the effects of heat stress on physical grain quality. Delayed sowing (i.e., July and August) increased the likelihood of daytime temperatures above 30°C during grain-filling. Supplementary irrigation of field trials ensured a reduced impact of drought stress. Heat tolerance appeared to be the primary factor determining grain plumpness. A wide variation was observed for heat tolerance, particularly among the Australian varieties. Genotypic variation was also observed for grain weight, plumpness, grain growth components, stay-green and stem water-soluble carbohydrates (WSC) content, and mobilisation under normal and delayed sown conditions. Compared to normal sowing, delayed sowing reduced duration of developmental phases, plant height, leaf size, head length, head weight, grain number, plumpness, grain width and thickness, stem WSC content, green leaf area retention, and harvest index (HI), and increased screenings, grain length, grain-filling rate (GFR), WSC mobilisation efficiency (WSCME), and grain protein content. Overall, genotypes with heavier and plumper grains under high temperatures had higher GFR, longer grain-filling duration, longer green leaf area retention, higher WSCME, taller stature, smaller leaf size, greater HI, higher grain weight/plumpness potentials, and earlier flowering. GFR played a significant role in determining barley grain weight and plumpness under heat-stress conditions. Enhancing GFR may provide a new avenue for improving heat tolerance in barley.